some of you know i do competitive logic puzzles, especially variant sudoku. i used to hold some two not touch speedsolving records but those days are long past.
i've been thinking for a while of writing a textbook using puzzle solving to build up "the mathematical way of thinking" and leading the reader into using an enjoyment of puzzles to learn to read, write, and apply rigorous math proofs
there's probably not much of a market for it, but clever teenagers might benefit i guess